One of the psychological tricks some people fall prey of is that of being called vain. This is especially true when it comes to the case of adequate attention or concern about the way they look and how others perceive them in their walk through life. The label tends and in many cases achieves in making them feel guilty or reprehended. A given sense of having done something wrong. 
Let us analyze what is fair and what not. Of course, humans can act with certain vanity in some instances of life, maybe in the way they act towards the others but does it relate in any manner to the desire of looking better, feeling better?

The notion of vanity comes from the Latin word vanitas, which means that something is hollow, someone who pretends being that which the person is not, excessive pride.
Anybody who undergoes any type of intervention or procedure to improve his or her appearance sounds to me like a person who is not happy with oneself, does not identify with the person he or she is at the moment. That would be vain, and empty: living in a body that one does not appreciate, living ashamed or conscious of oneself before the others. There is never anything excessive in bringing our features to the place where they make us feel happy and whole. Even in the cases where people have seemingly gone too far in their attempts to shape themselves, the underlying desire and goal is always to reach that mental state in which we are at peace with our inner selves, and external image. It is not vanity, rather the appropriate kind of love we should always have toward ourselves.